Snap-action drive mechanism



Oct. 13, 1964 w, MOCARTY 3,153,188

SNAP-ACTION DRIVE MECHANISM Filed Aug. 1, 1962 4 Sheets-Sheet 1 nvne-wra I? W/LLAED E.

M G/IE7) Oct. 13, 1964 w. R. MOCARTY 3,153,188

SNAP-ACTION DRIVE MECHANISM Filed Aug. 1, 1962 4 Sheets-Sheet 2 f M MW 1964 w. R. MCCARTY 3,153,188

SNAP-ACTION DRIVE MECHANISM Filed Aug. 1, 1962 4 Sheets-Sheet 3 1964 w. R. MCCARTY 3,153,188

SNAP-ACTION DRIVE MECHANISM Filed Aug. 1, 1962 4 Sheets-Sheet 4 United States Patent 3,153,188 I SNAlP-ACTIGN Dill? E MECHANISM Willard a. McCarty, Sycamore Hills, Mo., assignor to Wagner Electric Corporation, St. Louis, Mo., :1 corpo ration of Delaware Filed Aug. 1, 1962, Ser. No. 214,120 21 Claims. (Cl. 323-435) The present invention relates to circuit control devices and more particularly to switching mechanisms suitable for use in transformer tap changing apparatus.

in a tap changing apparatus, such as used in step voltage regulators, the voltage of the circuit in which it is used is adjusted or controlled by moving a movable contact of a tap-selecting switch from electrical contact with one winding tap to another tap. The switch operating or drivins mechanisms for eficcting tap changes often include means for translating a relatively slow movement into a rapid snap action in order to obtain a quick break between the movable contact and the stationary contact of the tap-selecting switch. In the past, such mechanisms have been relatively complicated and expensive because of the relatively lar e number and size of the parts required.

It is a general object of the present invention to provide a new and improved mechanism for moving an element from one operating position to another with a snap action.

Another obiectof the present invention is to provide an improved driving mechanism for moving an element from one operating position to another with a snap action which is especially simple in construction and yet highly efiicient and reliable in operation.

Another object is to provide a suspecting switch operating mechanism requiring relatively few and simple parts and which provide a compact mechanism requiring a relatively small amount of space.

Another object is to provide a new and improved transformer tap changing apparatus having a tap changing switch operated by a snap-acting switch driving mechnism wihch is relatively simple and inexpensive to manufacture.

Another object is to provide in a transformer tap changing device a new and improved driving mechanism for operating a tap selector switch and a winding reversing switch.

Still another object is toprovide in a transformer tap changing apparatus having a tap-selecting switch and a transformer winding reversing switch, an improved reversing switch operating mechanism which is relatively simple and which substantially eliminates or minimizes undesirable static discharges between the movable and stationary contacts of tie reversing switch during operation.

Briefly, in accordance with one aspect of the present invention, a mechanism is provided which includes driven and driving members having resilient means coupled therebetween to impart'snap action movement, to the driven member between operative positions thereof, and a pair of holding means, one of the holding means being releasably engageable with the driven member to prevent movement thereof until a predetermined amount of energy is stored in the resilient means by movement of said driving member, and the other of the holding means being releasably engagable with the driven member to stop the driven member upon movement thereof to another operating position. The invention also consists in the parts and arrangement and combination of parts hereinafter described and claimed. p

The above and other objects and advantages of the present invention will become apparent from the following description and accompanying drawings wherein:

FIG. 1 is a front elevational view with parts broken 3,153,188 Patented Oct. 13., 1964 ice away of a transfom er tap changing mechanism embodying the present invention.

FIG. 2 is a sectional view taken along the line 2-2 of FIG. 1,

FIG. 3 is a front elevational view of the switch assembly of FIG. 1 together with a schematic wiring diagram of a voltage regulating system employing the tap changing mechanism of FIG. 1, and

FIGS. 4 and 4:: show a portion of the switch operating mechanism of FIGS. 1 and 2 in successive stages of operation.

Referring now to the drawings and more particularly to FIGS. 1 and 2, there is shown a transformer tap changing mechanism ltl including a frame 12, a reversible motor 14 mounted to the top of the frame, an electrical switch assembly 16 secured to the frame, and a switch operating or driving mechanism, indicated generally at 18, for operating the switch assembly.

Switch assembly 16 includes an insulating panel 29, a

dial type switch 22 and a transformer winding reversing switch 24. a

The dial switch 22, shown also in FIG. 3, includes a plurality of stationary contacts 25 circumferentially arranged on the panel 2%, and a movable contact member 26 mounted in the center of the stationary contacts for selective rotation into and out of contact with the stationary contacts. The stationary contacts 25 are adapted for connection to different taps along a transformer winding 27. The movable contact member 2d includes a pair of contacts 28 and 35% mounted on an insulating movable contact carrying plate 32 in spaced insulating relation with one another. The two movable contacts 28 and 36 are circumterentially spaced from each other relative to the spacing between adjacent stationary contacts 25 so that they either both engage one stationary contact 25 or they bridge adjacent stationary contacts. Contacts 23 and 31% are secured to current conductive mountings 34 and 35, respectively, which are in turn fixed to plate 32. Plate 32 is rotatable on a shaft 36 which is fixed to panel Ztl. A terminal stud 37 extends through panel 24 and is received in a mounting plate 33 for the shaft 36. A brush contact 3% secured to mounting 35 engages shaft 36 to provide a conductive connection between contact Elli and stud 37. A conductive ring 40, whichis mounted on panel 2t} concentric with shaft 36, is engaged by a brush contact 41 on mounting 34 to provide a conductive connection between a terminal stud 42 connected to ring 49 and contact 28. Stationary contacts 25 are fixed to the inner side of the panel 26 by studs 44 (one shown) which serve as lead terminals for connecting the stationary'contacts to difierent taps on winding 27. The stationary contacts 25 are sequentially identified as contacts 25a through 25L While the switching mechanism 18, which will be described in detail hereinafter, may be operated manually, such as by manually operating motor control switches (not shown), automatic control means is indicated in block form in FIG. 3. In the voltage regulating system schematically illustrated, the tapped winding 27 and a winding 45 are windings of an autotransformer. Winding 27 is a series winding, portions of which can be connected in series between an alternating current supply source 46 and a load 47 through the dial switch 22, and the winding 45 is a shunt Winding connected across the load. A conventional switching reactor 48 has its opposite ends connected respectively to the movable contacts 28 and 30 by providing leads between studs 37 and 42 on panel 20 and the opposite ends of the reactor winding, respectively. One side of the supply source 46 is a) winding is connected to the neutral stationary contact indicated at 251'. The motor 14, which supplies the mechanical power for operating the switching mechanism 19, is controlled by motor control means indicated in block form at 50. Various well-known types of suitable control circuits may be used to control the operation of the motor in response to changes in load voltage beyond predetermined limits in order to maintain the load voltage substantially constant or within predetermined limits. In voltage regulating systems such motor control systems include voltage sensing circuits responsive to the voltage across the load for operating the tap changing motor which, in turn, controls the effective transformation ratio of the transformer by inserting different portions of the tapped winding into the system. The motor 14 rotates at a relatively slow constant speed of rotation which is converted by the switch operating mechanism 18 into a rapid snap action movement of the movable contact member 26 so that as a movable contact of dial switch 22 leaves a stationary contact, undesirable arcing is avoided.

The reversing switch 24 includes a movable contact member 52 secured to a conductive mounting 54 mounted for rotation on a shaft 55 fixed to panel 20. Contact member 52 is engageable with one or the other of two spaced stationary contacts 56 and 57 secured to panel 20. A brush contact 53 secured on mounting 54 continuously contacts shaft 55 to provide an electrical connection between one of the stationary contacts, 56 or 57, and a terminal stud portion 59 of shaft 55. The two stationary contacts of the reversing switch 24 are connected to the opposite end taps of winding 27 while the movable contact 52 is connected by a lead from stud 59 to the neutral stationary contact 25i of the dial switch 22. Switch 24 permits the reversal of the connections of tapped winding 27 relative to the power supply source 46 so that the same winding can be used for both voltage boosting and bucking effects.

The switch operating mechanism 18 includes a driving member shown as a sprocket 68 driven by motor 14 by means of a drive chain 7th. A driven switch actuating member 72 is coupled to the sprocket 68 through resilient, energy storing connection means shown as including a pair of coil springs 74 and 76 each having one end connected to the sprocket 68 and the other end thereof connected to actuating member 72. The sprocket 68 and driven member 72 are mounted for rotation on a shaft 77 secured to the frame 12. Thesprings 7 and 76 are connected between the sprocket 68 and driven member 72 symmetrically on opposite sides of shaft 77 such that rotation of the sprocket relative to the driven member in either direction tensions one spring while tending to compress the other. The forces of springs 74 and 76 act along lines parallel to the planes of the driving and driven members.

The driven member 72 is in the form of an annular index plate provided with a plurality of circumferentially spaced notches 78 formed in the periphery thereof to provide spaced abutments which cooperate with releasable holding means shown as a pair of spaced detent assemblies St} and 82 fixedly mounted, such as by welding, to frame 12 adjacent the periphery of index plate 72. The notches '78 are sequentially identified as notches 78a through 78i. The detent assemblies 80 and 82 include pivotal latch members 84 and 86 biased by springs 88 and 89, respectively, toward the periphery of the index plate, the latches being engageable with the notches 78. The detent assemblies are circumferentially spaced relative to the spaces between notches 78 such that when one of the latch members is in a notch the other latch member is mid-way between two adjacent notches. The index plate 72 is coupled to the movable contact member 26 by means of an actuating pin 99 fixed to plate 72 radially between the center and periphery thereof. The actuating pin 99 extends axially outwardly passing into an opening or slot 91 formed in the contact carrying plate 32. With disposed between the sprocket and index plate.

As seen in FIG. 1, the cam member 92 is in the form of a nine pointed star shaped annular plate having at its periphery alternating oppositely-sloping edge surfaces 96 and 28 serving as cam surfaces. Pairs of adjacent diverging cam surfaces 96 and 93 define nine symmetrically disposed points 99 of the star. The points 99 extend radially outwardly slightly beyond the peripheral edge of index plate 72 so that the cam surfaces positively cam out either of the latches 84 and 86 during switching operations. Between each pair of adjacent points 99 the diverging edge surfaces 96 and 98 extend inwardly to a point radially inwardly of the bottom of each notch to permit one of the latches to enter a notch 78 during a switching operation. In a normal steady state condition of the apparatus the forces of springs 74 and 76 balance one another, and the cam is predeterminately positioned relative to the index plate 72 so that each end of a cam point 99 is disposed between two adjacent notches. In this way, one of the latches will always be in position to enter a notch after the other latch is cammed out of a notch to thereby stop the index plate '72 in its new position.

During a switching operation, one of the cam surfaces, as or 98, depending on the direction of rotation, disengages the latch holding the index plate after one of the springs, '74 or 76, has been tensioned to permit rotation of the index plate, while the cam permits the other latch to enter another notch 78 to stop the index plate in its next operating position. More specifically, one of the cam surfaces 98, for rotation of cam 92 in a clockwise direction, as viewed in FIG. 1, serves as a leading cam surface for engaging and moving one of the latches, 8 2- or 86, out of a notch 73, the cam permitting the other latch to engage or move into another notch 78 after the index plate has rotated a predetermined distance during a switching operation. When the cam 92 is rotated in the opposite direction, one of the surfaces 96 acts as a leading canr surface for engaging and moving one of the latches, S4 or do, out of a notch 78, the cam permitting the other latch to move into another notch '73 after the index plate has rotated a predetermined distance. Since one latch is located circumferentially midway between two adjacent notches 73 when the other latch is disposed in a notch, the index plate rotates with a snap-action movement through an arcuate distance equal to one half the distance between adjacent notches during each switching operation.

There are as many notches 78 and cam points 29 as there are stationary contacts 25 of the dial switch. in the embodiment shown for illustration in the drawings, there are nine equally spaced stationary contacts 25, nine cam points 99, and nine equally spaced notches 78 in the index plate 72. The number of notches, cam points, and switching positions may, of course, vary in accordance with the particular design. The arcuate distance between the centers of adjacent notches corresponds to the arcuate distance between the centers of adjacent stationary con tacts 25. Since the index plate rotates a distance equal to one half the distance between adjacent notches, there are eighteen operating positions for one complete revolution of the index plate. Correspondingly, the dial switch 2?. has nine alternate positions in which both movable contacts 28 and 3t) are in engagement with the same stationary contact, and nine alternate positions in which the movas able contacts bridge two adjacent'stationary contacts, during one complete revolution of the index plate. 7

In describing the operation of the tap changing apparatus shown in the drawings, it will first be assumed that the motor 14 is unenergized, the switching mechanism is is in abalanced steady state condition, such as indicated in FIG. 1, and that both contacts Ztl and 3% of movable contact member 26 are in contact engagement with a stationary contact a, and the reversing switch is in its voltage boosting position, the condition indicated in FIG. 3.

Upon the occurrence of a predetermined change in the voltage across load 47, such as an increase in voltage above a predetermined desired value, the motor control system will energize motor 14 to drive the switch operating mechanism in the proper direction tomake a tap change so as to change the transformation ratio of the auto-transformer and compensate for the change in load voltage, and in this case, reduce the voltage at the load to within desired limits. The motor will drive sprocket 63 and cam 92 by means of drive chain 7d at a relatively slow constant speed oi rotation in a counterclockwise direction, as viewed in FIG. 1. With latch 8 in a notch 78a, the sprocket and cam members will rotate relative to index plate 72. This rotation of the cam and sprocket members causes spring 74 to be tensioned and thereby store energy. As the leading cam surface eta rotates, it engages and moves latch radially outwardly, and when latch 84 is moved completely out ofnotch 75in, the force of tensioned spring 7 1 causes the index plate 72 to rotate rapidly with a snap action movement in a direction to catch up with the cam and sprocket members. The index plate rotates during this snap action movement until latch ltd enters notch 78; to stop the index plate. The index plate will now be positioned relative to the latches 84 and tid, and the cam and sprocket, as indicated in FIG. 4. This snap action movement of the index plate, of course, causes the contact member 26 to move witha snap action to its next successive operating position which is a contact bridging position wherein the contact 3d remains in engage'men't with the stationary contact 25a. while contact 23 is now in engagement with contact 2512.

If another tap change in the same direction is required by the voltage sensing and motor control system inorder to reduce the load voltage to its desired normal value, the motor will again be energized or will continue to be energized to effect another tap change. In such case, latch Elli, which is now in a notch 731', will hold index plate '72 stationary until the cam and sprocket have again rotated to tension spring 74. After leading cam surface see engages and moves latch out of notch 731', the index plate will rapidly rotate with a snap-action movemen-t until latch 34 enters notch 7812, as seen in FIG. 4a. This will cause movable contact member as to be moved with a snap action movement to the next operating position wherein both contacts 23 and are in engagement with stationary contact 25b.

For successive tap changes in the above direction, the switching mechanism ldwill operate in a manner similar to that described above, the latches 84 and 8d alternating with each other in holding and stopping the index plate.

Operation of the switching mechanism in the reverse direction is similar to the hereinbefore described operation except that when the sprocket and cam rotate in the clockwise direction, cam surfaces 93 selectively operate the latches 3d and 86, and spring 76 provides the force for effecting the snap action rotation of index plate 72. For example, if the. switch operating mechanism is in'the condition indicated in FIG. 4a, and themotor control system energizes motor 14 so that it runs in the opposite direction, the index plate will be driven with a snap action movement in the clockwise direction to its next operating position which will be that indicated in FIG. 4; The

index plate, in moving from its position in FIG. 4a to that of FIG. 4, is held stationary by latch 84 until cam surface 935w disengages'latch 34, and then te nsioned spring ill effects the snap action rotation of the index plate, the index plate stopping when latch 86 enters notch 782'. Further rotation of the sprocket and cam to effect another tap change in the same direction will returnthe index plate to the position shown in FIG. 1. In so returning, the index plate will first be held stationary by latch 86 until the sprocket has tensioned spring 76 and the cam surface 9315 has disengaged latch 86. The index plate will rotate until latch 84 enters notch 78a.

With the springs '74 and '75 predcterminately tensioned when the apparatus is in a normal steady state condition, one of the springs, depending on the direction of rotation, will ellect the rapid snap action of the index plate, as previously described herein, while the other spring will snub or retard the index plate near the end of a snap action movement or as the index plate approaches its next position. This snubbing action by one of the springs '74 and during each snap action movement of the index plate reduces the mechanical shock and noise during operation of the switching mechanism.

When the movable contacts 2% and 30 are in engage ment with stationary contact 25a and movable contact 52 of the reversing switch is in contact with stationary con tact 5'7, its voltage boosting position, the tap changer is in its maximum boosting position. If the contacts 28 and 30 are rotated in a clockwise direction, as viewed in FIG. 3, the boosting voltage effects will decrease as the contacts rotate from one stationary contact to another. When the contacts 28 and 39 are in engagement with stationary contacts 251' and 25h, respectively, the tap changer is in its minimum boosting position. When both contacts 23 and 30 are in engagement with contact 252' the entire winding 27 is disconnected from the power circuit and the tap changer is in its neutral or zero boosting or bucking position. If the reversing switch, the operation of which will be described in detail hereinafter, is operated to its other position or bucking position, rotation of the tap-selecting contacts 23 and 3d in the clockwise direction will result in increasing voltage bucking etfects as the contacts 23 and 3% move into engagement with successive stationary contacts. Under these conditions, when both contacts 23 and 31? are in engagement with contact 25h, the tap changer will be in its maximum bucking position. Thus, in the embodiment shown in the drawings, there are a total of sixteen voltage'boosting or raise switch positions, sixteen voltage bucking or lower positions, and a neutral position.

The movable contact member 2 3 of the dial switch is always positively disposed in one of itsoperatin'g positions regardless of the operation'of the motor or motor control system, i.e., the contact member as is never stopped with one ofits contacts disengaged from a stationary contact. This is because one of the detent assemblies, 8t} or 32, maintains the index plate and movable contact member 26 of the dial switch 22 in an operating position until the holding detent is unlatched by cam 92-, and then the rotation of the index plate and contact member 26 to the next operating position is independent of the operation of the driving member or motor. Should the motor begin rotating the driving member 68, but then stop before cam 92 has completely unlatched one of the detent assemblies, the index plate will still remain in its operating position because of the holding detent, and the tensioned spring will tend to return the cam and driving member back to a normal position.

In the construction shown in the drawings, the reversing switch 24 is actuated so that movable contact is moved from engagement with stationary contact 57 to engagement with stationary contact as as the movable tap selecting contacts are moved from the bridging position in which the contact 28 engages stationary contact 25i and contact 3th engages contact 257:, the minimum voltage boosting position, to the neutral position wherein both movable contacts are in engagement with the neutral cona tact 251'. If the tap selecting contacts are moved in the opposite direction from the neutral position to the minimum boosting position, the reversing switch will be actuated so as to move its contact 52 from stationary contact 56 to stationary contact 5'7 The reversing switch 24- is actuated by a pivotal operating member, which is shown in the drawings in the form of a Geneva gear sector ltlll, coupled to the movable contact carrying member 54. Sector is mounted for limited rotation on a shaft 102 fixed to the frame 12. Mounting member is provided with an actuating pin 1W;- radially displaced from its shaft $5 and which extends axially into a slot 1% of a driving member list; fixed to the sector lltlll. The sector Fri l? is mounted on the shaft 1.132 adjacent the peripheral edge of i1" ex plate '72 and is provided with a pinion receiving slot 116 and arcuate Geneva locking surfaces 132 and lid on opposite sides of the slot 110. A Geneva gear actuating pinion llld is fixed to the index plate adjacent the periphery thereof and is engageable with the sector 1% for actuating the reversing switch. In the illustrated embodiment, the index plate is provided with an integral ring member 118 adjacent the left hand side thereof, as viewed in FIG. 2, which has an annular peripheral surface 120. The areaate locking surfaces 112 and ill l cooperate witr peripheral surface 129 to prevent rotation of the sector and maintain the sector and reversing switch a locked position until actuated by pinion 116. The pinion 116 extends axially outwardly of the left hand side of the index plate and is adjacent a recess 122 formed in the peripheral surface 12%? so that as pinion 116 engages and enters slot lltl, the sector tee is permitted to rotate on shaft lliZ with a portion thereof passing through recess 122. Pinion lie is located on index plate ?2 relative to the dial switch 22 so that it engages and actuates sector such that the movable contact 52 moves from engagement with stationary contact 57 to engagement with contact 5'6 during movement of the tap selecting movable contact 26 from the minimum boosting position to the neutral position. The movable contact 52 will, of course, return to engagement with contact 56 upon movement of contact 26 from the neutral position to the minimum boosting position.

Because the reversing switch actuating pinion is disposed on the index plate 72, the reversing switch is moved from one operating position to the other with a rapid snap action movement. The reversing switch is operated by the index plate during a snap action movement thereof so that the movable contact 52 is positively positioned in one or the other of its operating positions. When the movable contact of a reversing switch is moving between its associated fixed contacts, the tapped winding is isolated from the rest of the circuit and may pick up static voltage from another winding coupled thereto, such as the shunt winding 45. This usually produces discharge sparks between contacts of the reversing switch and radio disturbances. However, because the reversing switch 2 5 of the instant device is actuated with a snap action, the period of time that the movable contact 52 is between the fixed contacts as and 57 is very short, and such radio dist rbance is substantially eliminated or minimized. Also, this snap action movement of movable contact 52 is accomplished simply by employing an actuating pinion lid on the snap acting index plate '72 which is engageable with the Geneva gear sector 11%.

The switching mechanism 18 is also provided with a mechanical limit stop device to prevent the possibility of movement of the movable contact 26 of the dial switch beyond the maximum boosting and bucking positions. The limit stop device shown in FIGS. 1 and 2 includes a rocker plate pivotal on shaft 162-, and an abutment member shown as a pin 126 secured to cam 92 which is engageable with the rocker plate 124. Plate 24 is pivotal between two positions in response to movement of the reversing switch 24, one position in which an end (h is 128 thereof is in the path of the stop pin 126 when the reversing switch is in its volttge boosting position and in dex plate 72 is rotating in a clockwise direction, as viewed in FIG. 1, and another position wherein an opposite end 1369 is in the path of pin 126 when the index plate 72 is rotating in the opposite or counterclockwise direction and the reversing switch is in its voltage bucking position.

The rocker plate 124 is operated and held in either of its positions by an upper portion 132. of the Geneva gear sector 1% of the reversing switch. The portion 1322 extends over the upper edge of the rocker plate 124, and when the sector is pivoted, one side of the upper portion 132 engages the upper edge of the rocker plate at a point between its axis of rotation and one of the end portions thereof to move that end portion into the circular path of the stop pin 126. When the end portion 128 of the rocker plate is moved by the sector 1% into the position shown in FIG. 2, the other end portion 136 engages an abutment 13d fixed to frame 12 to thereby posi tively position the rocker plate. Similarly, when sector 1% operates the rocker plate into its other position, wherein the end portion 13h is moved into the path of stop pin 126, the end portion lZS engages an abutment 1355 to hold the rocker plate in proper position.

The stop pin 126 is located on cam 92 adjacent the reyer-sing switch pinion lid. The pinion and stop pin 126 are circumferentially spaced apart less than one half the distance between notches 73 when the mechanism is at rest. Thus, when the index plate is rotated and the pinion 116 actuates the sector lliltl and the rocker plate 124-, the stop pin freely passes under the rocker plate. Should the index plate be driven by the sprocket far enough in the same direction, the stop pin lid on cam 92 will engage one end of rocker plate 124 and prevent further movement of the sprocket and index plate. The stop pin 126 is located on cam 92 relative to the movable contact 26 of the dial switch such that, if the mechanism attempts to move the movable contact member 26 of the dial switch beyond the maximum boost or bud J switch position, one of the ends 128 and 13d of the rocker plate will be engaged by pin 1% to prevent further movement of the sprocket and index plate.

With this construction, the limit stop plate 124 is always positively actuated and maintained in proper position by the reversing switch mechanism to prevent an undesired movement of the dial switch contact member 26 beyond the maximum boost or buck position.

The switch operating mechanism lll may be conveniently secured within an oil-filled compartment of a main casing (not shown) containing the transformer windings, and lead connections between the various switch contacts and transformer windings may he made within the casing, as is well known to those skilled in the art.

It is now apparent that the hereinbefore described tap changing apparatus embodying the present invention is relatively simple in construction, reliable in operation, and requires relatively few parts which, when assembled, form a very compact unit.

it is now apparent that a novel circuit control device meeting the objects set out hereinbefore is provided and that changes and modifications in the disclosure may be made by those skilled in the art without departing from the spirit of the invention as defined by the claims which follow.

What I claim is:

l. A mechanism for moving an element from one operating position to another with a snap action comprising a driven member coupled to said element, driving means for said driven member, resilient means coupling said driven member with said driving means, resiliently urged holding means normally biased into operative holding engagement with said driven member to prevent movement of said driven member until a predetermined amount of energy is stored in said resiliei means in response to movement of said driving means relative to said driven member, means movable with said driving means to engage and move said resliently urged holding means out of operative holding engagement with said driven member to permit snap action movement of said driven member in response tothe stored energy of said resilient means, and other resiliently urged holding means normally biased toward said driven member, said other resiliently urged holding means being movable into sliding engagement with said driven member and subsequently into operative holding engagement with said driven member to stop said driven member and predeterminately limit the snap action movement of said element.

2. A mechanism for moving an element from one operating position to another with a snap action comprising a driven member coupled for concert movement with said element, driving means for said driven member, resilient means coupling said driven member with said driving means, holding means for said driven member including a pair of resiliently urged latch members, one of said latch members being normally biased into holding engagement with said driven member to prevent movement of said driven member until a predetermined amount of energy is stored in said resilient means in response to movement of said driving means relative to said driven member, and means movable in accordance with movement of said driving means to bias said one resiliently urged latch member from holding engagement and permit snap action movement of said driven member and element in response to the stored energy of said resilient means, the other of said resiliently urged latch members being normally biased toward dwelling engagement with said driven member and movable into operative holding engagementwith saiddriven member to stop said driven member upon predetermined snap: action movement.

3. A mechanism for moving an element from one operating position to another witn a snap action comprising a driven member coupled to said element and having a plurality of successively spaced abutments thereomdriving means for said driven member, resilient-means coupling said driven member with said driving means, resiliently urged means normally biased into engagement with one of said abutments to prevent movement of said driven member and edect the storage of a predetermined amount of energy in said resilient means in response to movement of said driving means relative to said driven member, means movable with said driving means to disengage said resiliently urged means from said one abutment and permit snap action movement of said driven member in response tothe stored energy'insaid resilient means, and other means normally urged toward engagement with said driven member, said other means being movable into sliding engagement with said driven member between successive abutments thereon and movable into holding engagement with one of said abutments to predeterminately limit the snap action movement of said driven member. p

4. A mechanism for movin an element from one operating position to another operating position with a snap action movement comprising a driven member coupled to said element and having a plurality of spaced abutments thereon, driving means for said driven member, resilient means coupling said driven member with said driving means, holding means for said driven member including a pair of latch members biased toward engagement with said driven member, one of said latch members being releasably engageable with one of said abutments to prevent movement of said driven member until a predetermined amount of energyis stored in said resilient means by movement of said driving means, and means movable in accordance with movement of said driving means to release said one latch member from said one abutment and effect snap action movement of said driven member, said other latch member being releasably engageable with one of said abutments to stop said driven member after said driven member has moved a predetermined distance.

I lit 5. A mechanism for moving an element from one operating position to another operating position with a snap action movement comprising a driven member coupled to said element and having a plurality of equally spaced abutments thereon, driving means for said driven member, spring means coupling said driven member with said driving means, holding means for said driven member including a pair of latch members each biased toward engagement with said driven member, one of said latch members being releasably engageable with one of said abutments to prevent movement of said driven member until said spring means is tensioned to a predetermined extent by movement of said driving means, and cam means on said driving means to engage and release said one latch member from said one abutment to eifect movement or said driven member and permit said other latch member means, movable holding means releasably engageable with said driven member in one operating position thereof to prevent rotation of said driven member until a predetermined amount of energy is stored in said resilient means by rotation of said driving means, cam means on said driving means and rotatable therewith to engage and release said holding means, said resilient means serving to effect snap action rotation of said driven member relative to said driving means and toward another operating position upon release of said holding means, and other holding means normally biased toward said driven member and movable into releasable engagement with said driven member to stopsaid driven member after it has rotated at predetermined' distance. i

7, A mechanism for moving an element from one operating position to another operating position with a snap action comprising a driven member rotatable about an axis and coupled to said element, said driven member hav ing a plurality of spaced abutments thereon, driving means for said driven member rotatable about said axis, resilient means connected between said driven member and said driving means, holding means for said driven member in cluding a pair of releasable latch members resiliently biased toward engagement with said driven member, one of said latch members being releasably engageable with one of said abutments to prevent rotation of said driven member until a predetermined amount of energy is stored in said resilient means'by rotation of said driving means, and cam means on said driving means to release said one latch member from said one abutment and eifect rotation of said driven member, said other latch member being releasably engageable with one of said abutments to stop said driven member after said driven member has rotated a predetermined distance.

8. A mechanism for moving an element from one operating position to another operating position with a snap action comprising a driven member rotatable about an axis and coupled to said element, said driven member having a plurality of equally spaced abutments at the periphery thereof, driving means for said driven member rotatable about said axis, spring means connected between said driven member and said driving means, holding means for said driven member including a pair of releasable latch members biased toward engagement with said driven member, one of said latch members being releasably engageable with one of said abutments to prevent rotation of said driven member until a predetermined amount of energy is stored in said spring means by rotation of said is it engageable with said one latch member for releasing said one latch member from said one abutment to effect rotation of said driven member, one of said abutments being engageable with the other of said latch members to stop said driven member after said driven member has rotated a predetermined distance.

9. A switch operating mechanism for moving a contact element ofa switch from one switch operating position to another operating position with a snap action comprising a frame, a driven member mounted for rotation on said frame and coupled to said element, said driven member having a plurality of equally spaced peripheral abutments, a driving member mounted for rotation on said frame in coaxial relation with said driven member, electric motor means coupled to said driving member for rotating said driving member at a relatively slow speed, spring means connected between said driven member and said driving member, a pair of spaced apart releasable latch mem ber mounted to said frame adjacent the periphery of said driven member and biased toward engagement with said driven member, one of said latch members being releasably engageable with one of said abutments to prevent rotation of said driven member until a predetermined amount of energy is stored in said spring means by rotation of said driving member, and an annular cam member on said driving member having a plurality of cam surfaces at the periphery thereof engageable with said latch members, one of said cam surfaces being engageable with said one latch member to release said one latch member from said one abutment for effecting snap action rotation of said driven member, said other latch member being releasably engageable with one of said abutments to stop said driven member after said driven member has rotated a predetermined distance.

10. A tap changing mechanism comprising a main transformer winding and a tapped transformer winding adapted for connection in an electrical circuit, a tap selecting switch including a plurality of spaced stationary contacts connected to taps on said tapped winding, and a movable contact iember engageable with said stationary contacts for connecting said tapped winding with said main winding, and means for moving said contact member from engagement with one of said stationary contacts to the next stationary contact with a snap action comprising a drivenmernber coupled to said contact member for movement therewith, driving means for said driven member, resilient means coupling said driven member with said driving means, movable holding means resiliently biased toward and releasably engageable with said driven member to hold said driven member and said contact member in engagement with said one stationary contact until a predetermined amount of energy is stored in said resilient means by movement of said driving means, cam means movable in concert with said driving means to engage and release said holding means and effect movement of said driven member, and other movable holding means resiliently biased toward and releasably engageable with said driven member to stop said driven member after said driven member has moved a predetermined distance to position said contact member in engagement with said next stationary contact.

11. A tap changing apparatus comprising a tapped transformer winding, a tap changing switch including a plurality of circumferentially spaced stationary contacts connected to different points along said winding, and a movable contact member engageable with said stationary contacts to provide a plurality of operating positions, and means for moving said contact member from engagement with one of said stationary contacts to the next with a snap action movement comprising a switch actuating member coupled to said contact member and having a plurality of notches formed therein, rotatable driving means for rotating said actuating member, resilient energy storage means coupling said actuating member to said driving means, holding means mounted for cooperation with said notches to position said contact member in said operating positions, said holding means including a pair of latch members releasably engageable one at a time with said notches, one of said latch members being engageable with one of said notches to prevent rotation of said actuating member during a predetermined rotation of said driving means to effect the storage of energy in said resilient means, and a cam member on said driving means and having a plurality of spaced cam surfaces thereon, one of said cam surfaces being engageable with said one latch member to disengage said one latch member from said one notch after said driving means has rotated a predetermined distance to thereby effect snap action rotation of said actuating member and said contact member, one of said notches being engageable with the other of said latch members after said actuating member has rotated a predetermined distance to stop said actuating member and said contact member in said next operating position.

12. A switch operating mechanism for moving a contact element of a switch from one switch operating position to the next with a snap action comprising a frame, a driven member coupl d to said element and mounted on said frame for rotation about an axis, said driven member having a plurality of equally spaced notches at the periphery thereof, a driving member mounted for rotation in either direction on said frame in coaxial relation with said driven member, a pair of spring means connected between said driven and driving members and disposed on opposite sides of said axis, a pair of spaced pivotal latch members mounted to said frame adjacent the periphery of said driven member and biased toward engagement with said driven member, and an annular cam member on said driving member having first and second groups of symmetrically disposed cam surfaces at the periphery thereof with the cam surfaces of said first group alternating with the cam surfaces of the second group, said first group of al ernate cam surfaces being 'engageable with said latch members for one direction of rotation of said cam member, said second group of alternate cam surfaces being engageable with said latch members when said cam member rotates in the opposite direction, one of said latch members being engageable with one of said notches to prevent rotation of said driven member to effect the storage of a predetermined amount of energy in one of said spring means upon rotation of said driving member, one of said cam surfaces being engageable with said one latch member to release said one latch member from said one notch to thereby effect rotation of said driven member, one of said notches being engageable with the other of said latch members to stop said driven member after said driven member has rotated a predetermined distance.

13. A tap changing apparatus comprising a transformer winding having a plurality of taps, a tap-selecting switch for selectively connecting different portions of said winding in an electric circuit, said tap-selecting switch including a plurality of stationary contacts respectively connected to diiferent taps on said Winding, and a movable contact element engages le with said stationary contacts to define a plurality of transformer operating positions, a tap-selecting switch operating mechanism including an actuating member coupled to said movable contact elemenhand snap action driving means for moving said actuating member and said movable contact from one operating position to another with a snap action, a reversing switch including a pair of fixed contacts connected respectively to opposite ends of said winding, and a movable contact member adapted to be moved from engagement with one of said fixed contacts to the other with a snap action for reversing the polarity connections of said winding relative to said circuit when said reversing switch is actuated, and means for actuating said reversing switch in response to a predetermined snap action movement of said contact element from one predetermined operating position to another predetermined operating position, said last named means including a movable operating member coupled to said contact member for moving said contactmember in response to an applied force thereon, and an abutment member coupled to said actuating member for concert movement therewith and engageable with said operating member to apply a force thereto and move said operating member and said contact member with a snap action movement in response to said predetermined snap action movement of said contact element to actuate said reversing switch.

14. In a tap changing apparatus for an electrical circuit including a transformer having a tapped winding connected in said circuit, a tap-selecting switch having stationary contacts connected to different taps on said winding, and a movable contact element engageable with said stationary contacts to define a plurality of operating positions, and a reversing switch including a pair of fixed contacts connected respectively to opposite ends of said winding, and a movable contact member adapted to be moved from engagement with one of said fixed contacts to the other with a snap action for reversing the polarity connections of said winding relative to said circuit when said reversing switch is actuated, the combination therewith comprising a driving mechanism for moving said contact element from one position to the next position, said mechanism including an actuating member coupled to said contact element, a driving member, resilient coupling means connected between said driving and actuating members, latch means for preventing movement of said actuating member to effect the storage of a predeten mined amount of energy in said couplingmeans by movement of said driving member, and means for releasing said latch means to effect snap action movement of said actuating member and said contact element from one operating position'toward another, and means for actuating said reversing switch with a snap action movement in response to a predetermined snap action movement of said contact element from one predetermined operating position to another predetermined operating position, said last named means including a movable operating member coupled to said contact member for moving said contact member in response to an applied force on said operating member, and an abutment member connected to and movable in concert with said actuating member and engageable with said operating member to apply a force to said operating member and move said contact member from engagement with one of said fixed contacts to the other of said fixed contacts with a snap action movement in response to said predetermined snap action movement of said contact element. g

15. Atap changing apparatus for an electrical circuit comprising a transformer having a tapped winding connected in said circuit, a tap-selecting switch having stationary contacts connected to different taps on said winding, and a movable contact element engageable with said stationary contacts to define a plurality'of trans-former operating positions, a driving mechanism for moving said contact element from one operating position to the next with a snap action comprising an actuating member connected to said contact element, a drivingmember, spring means coupling said contact element to said driving member, releasable latch means for preventing movement of said actuating member to effect the storage of a predetermined amount of energy insaid coupling means by movement of said driving member, and means on said driving member for releasing said latch means to effect snap action movement of said actuating member and said contact element, a reversing switch for reversing the polarity connections of said winding relative to said circuit including a pair of fixed contacts connected respectively to the opposite ends of said winding, and a movable contact member engageable with said fixed contacts, and means for moving said contact member from engagement with one of said fixed contacts to the other or" said fixed contacts With a snap action during movement of said con tact element from a predetermined one of said operating positions to another predetermined one of said operating positions, said last named means including a Geneva gear sector coupled to said contact member and cooperating with said actuating member to normally hold said contact member in engagement with one of said fixed contacts, and an abutment member fixed to said actuating member and engageable with said sector to move said contact member from engagement with said one fixed contact to the other of said fixed contacts.

16. In a tap changing apparatus for an electrical circuit including a transformer having a tapped Winding connected in said circuit, a tap-selecting switch having stationary contacts connected to dillerent taps on said winding, and a movable contact element engageable with said stationary contacts to define a plurality of operating positions, and a reversing switch including a; pair of fixed contacts connected respectively to opposite ends of said winding, and a movable contact member adapted to be movedt'rom engagement with one of said fixed contacts to the other with a snap action for reversing the polarity connections of said winding relative to said circuit when said reversing switch is actuated, the combination therewith comprising a driving mechanism for moving said contact element from one position to the next position, said mechanism including an actuating member coupled to said contact element, a driving member, resilient coupling means connected between said driving and actuating members, latch means for preventing movement of said actuating member to effect the storage of a predetermined amount of energy in said'coupling means by movement of said driving member, and means for releasing said latch means to effect snap action movement or" said actuating member, means for actuating said reversing switch in response to movement of said contact element from one predetermined operating position to another predetermined operating position, said last named means including a movable operating member coupled to said contact member, and an abutment member movable in accordance with'said actuating member and engageable with said operating member to move said contact member from engagement with one of said fixed contacts to the other of said fixed contacts with a snap action movement, and a mechanical limit stop device for preventing movementof said movable contact element beyond predetermined extreme operating positions comprising a stop member connected with said driving member, and a stop plate movable between first and second operating positions by said operating member when-said reversing switch is actuated, said stop member being engageable with said stop plate to stop said driving member when said driving member is moving in one direction and attempts to move said movable contact element beyond one of said extreme operating positions and when said driving member is moving in the opposite direction and attempts to move said movable contact element beyond the other of said extreme operating positions.

17. In a tap changing apparatus for an electrical circuit including a transformer having a tapped Winding connected in said circuit, a tap-selecting switch having stationary cohtactsconnected to different taps on said winding, and a movable contact element engageable with said stationary contacts to define a plurality of operating positions, and a reversing switch including a pair of fixed cont acts connected respectively to opposite ends of said winding, and a movable contact member adapted to be moved from engagement with one of said fixed contacts to the other with a snap action for reversing the polarity connections of said winding relative to said circuit when said reversing switch is actuated, the combination therewith comprising a driving mechanism for moving said contact element from one position to the next position, said mechanism including an actuating member connected to said contact element, a driving member, resilient coupling means connected between said driving and actuating members, latch means for preventing movement of said actuating member to effect the storage of a predetermined amount of energy in said coupling means by movement of said driving member, and means for releasing said latch means to effect snap action movement of said actuating member, and means for actuating said reversing switch in response to movement of said contact element from one predetermined operating position to another prede termined operating position, said last named means including a movable operating member connected to said contact member, and an abutment member connected to said actuating member and engageable with said operating member to move said contact member from engagement with one of said fixed contacts to the other of said fixed contacts with a snap action movement, and a mechanical limit stop device for preventing movement of said movable contact element beyond predetermined extreme operating positions comprising a stop member fixed to said driving member, and a stop plate movable between first and second operating positions, said operating member engaging said stop plate to move said stop plate between said first and second positions when said reversing switch is actuated, said stop member being engageable with said stop plate to stop said driving member when said driving member is moving in one direction and attempts to move said movable contact element beyond one of said extreme operating positions and when said driving member is moving in the opposite direction and attempts to move said movable contact element beyond the other of said extreme operating positions.

18. A mechanism comprising a pair of relatively rotatable members, a pair of resiliently urged holding means, one of said holding means being normally in operative holding engagement with one of said members and the other of said holding means being normally out of operative holding engagement with said one member, the other of said members being rotatable relative to said one member a predetermined amount to engage and move said one holding means out of operative holding engagement, and resilient means coupling said members and stressed by the predetermined relative rotation of said other member to impart snap action rotation to said one member upon movement of said one holding means out of operative holding engagement, said other holding means being resiliently urged into operative holding engagement with said one member upon predetermined snap action rotation thereof relative to said other member to stop said one member.

19. Means for effecting snap action movement of a driven member between adjacent operating positions thereof comprising driving means, a pair of selectively movable holding means, one of said holding means being normally in holding engagement with said driven member and the other of said holding means being normally disengaged from holding engagement with said driven memer in one operating position thereof, cam means connected with said driving means and movable in response to predetermined movement of said driving means to initially disengage said one holding means from holding engagement with said driven member, and resilient means coupling said driving means and driven member and being stressed in response to movement of said driving means to effect snap action movement of said driven member toward the next adjacent operating position thereof upon the disengagement of said one holding means, said cam means providing for subsequent movement of said other holding means into holding engagement with said driven member to stop said driven member at the next adjacent operating position thereof.

20. A switch operating mechanism for moving a contact element of a switch from one of a plurality of switch operating positions to a next operating position with a snap action movement comprising a frame, a driven member coupled to said element and mounted for rotation to said frame, driving means mounted to said frame for rotating said driven member, resilient means coupling said driven member with said driving means, a pair of movable holding means connected to said frame and resiliently biased toward engagement with said driven member and movable into and out of operative holding engagement with said driven member, and cam means connected to said driving means for concert rotation therewith and selectively engagcable with said pair of holding means for selectively moving said pair of holding means out of operative holding engagement with said driven member, one of said holding means being in operative holding engagement with said driven member when said contact element is in said one operating position to prevent rotation of said driven member during a predetermined rotation of said driving means to effect storage of a predetermined amount of energy in said resilient means, the other of said holding means being out of operative holding engagement with said driven member during said predetermined rotation of said driving means, said cam means being engageable with said one holding means to move said one holding means out of operative holding engagement with said drivenmember to permit snap action movement of said driven member and said element from said one operating position in response to the energy stored in said resilient means, said cam means permitting said other movable holding means to move into operative holding engagement with said driven membe' to stop said driven member after said driven member has moved a predetermined distance to stop said element in said next operating position.

21. A tap changing apparatus comprising a tapped transformer winding, a frame, a tap selector switch assembly connected to said frame and including a plurality of cirrumferentially spaced stationary contacts con nected respectively to different taps on said winding, and a contact member rotatable in either direction and en gageable with said stationary contacts to define a plurality of switch operating positions, and a switch operating mechanism for moving said contact member from one of said operating positions to the next with a snap action movement comprising an annular actuating member mounted to said frame for rotation, said actuating member having a plurality of circumferentially spaced notches adjacent to the periphery thereof, a rotatable drive member mounted to said frame in axially spaced coaxial relation with said actuating member, a pair of spring means between said actuating member and said drive member with each having one end connected to said actuating member and the other end to said drive ember, a pair of latch members pivotally mounted to said frame adjacent to the periphery of said actuating member, resilient means biasing each of said latch members toward engagement with said actuating member with each of said latch members being selectively movable into and out of said notches, said latch members being circumferentially spaced apart relative to the spacing between said notches so that only one of said latch members at a time is in any of said notches, cam means connected to said drive member for concert rotation therewith, said cam means having surfaces thereon engageable with said latch members for selectively moving either of said latch members out of one of said notches in response to predetermined rotation of said drive member in either direction, one of said latch members being in one of said notches when said Contact member is in one of said operating positions to prevent rotation of said driven member and permit the storage of a predetermined amount of energy in one of said spring means in response to a predetermined amount of rotation of said drive member relative to said driven member, one of said cam surfaces being cngageable with said one latch member to move said one latch member out of said one notch only when the rotation of said drive member exceeds said References Cited in the file of this patent predetermined amount to permit snap action rotation of UNITED STATES PATENTS said actuating member and semi contact member from 6 said one operating position toward the next oyei'ating 139L101 Cmmt 131 1932 position, said .cam means permitting the other of said 7 H111 24,1939

latch members to move into one of said notches after 5 9 Schultz 1952 said actuating member has moved a predetermined dis- Bagulm Oct 1957 tance to stop said actuating member and said contact 23415U2 sfialey July 1958 2,947,838 Ureda Aug. 2, 1960 member in th next adjacent operating position. 

1. A MECHANISM FOR MOVING AN ELEMENT FROM ONE OPERATING POSITION TO ANOTHER WITH A SNAP ACTION COMPRISING A DRIVEN MEMBER COUPLED TO SAID ELEMENT, DRIVING MEANS FOR SAID DRIVEN MEMBER, RESILIENT MEANS COUPLING SAID DRIVEN MEMBER WITH SAID DRIVING MEANS, RESILIENTLY URGED HOLDING MEANS NORMALLY BIASED INTO OPERATIVE HOLDING ENGAGEMENT WITH SAID DRIVEN MEMBER TO PREVENT MOVEMENT OF SAID DRIVEN MEMBER UNTIL A PREDETERMINED AMOUNT OF ENERGY IS STORED IN SAID RESILIENT MEANS IN RESPONSE TO MOVEMENT OF SAID DRIVING MEANS RELATIVE TO SAID DRIVEN MEMBER, MEANS MOVABLE WITH SAID DRIVING MEANS TO ENGAGE AND MOVE SAID RESLIENTLY URGED HOLDING MEANS OUT OF OPERATIVE HOLDING ENGAGEMENT WITH SAID DRIVEN MEMBER TO PERMIT SNAP ACTION MOVEMENT OF SAID DRIVEN MEMBER IN RESPONSE TO THE STORED ENERGY OF SAID RESILIENT MEANS, AND OTHER RESILIENTLY URGED HOLDING MEANS NORMALLY BIASED TOWARD SAID DRIVEN MEMBER, SAID OTHER RESILIENTLY URGED HOLDING MEANS BEING MOVABLE INTO SLIDING ENGAGEMENT WITH SAID DRIVEN MEMBER AND SUBSEQUENTLY INTO OPERATIVE HOLDING ENGAGEMENT WITH SAID DRIVEN MEMBER TO STOP SAID DRIVEN MEMBER AND PREDETERMINATELY LIMIT THE SNAP ACTION MOVEMENT OF SAID ELEMENT. 